The Quarterly Journal of Economics Volume 28 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 edition. Excerpt: ...or corn-meal porridge. Here are two margins, and it is a question, not of logic but of fact, which counts. There can be little doubt that it is the latter, or margin of substitution, that is chiefly significant in price determination. We have, then, two conceptions of marginality, one of which may be described as logical, the other as effective. Logical marginality may attach to any unit of supply or any unit of demand; effective marginality attaches to particular units, determinable by fact and circumstance. Recurring to Davenport's analogy of the raft, the mathematician may safely indulge himself in curious speculation as to whether it is the last man who sinks the raft, or the first man, whose presence so burdens the raft that the last man will sink it. This is not the sort of speculation that men indulge in when in the presence of an emergency. The first man on the raft rejoices in its excess carrying capacity and is quite unconcerned about his own weight. He welcomes a second for his companionship, and a third. With ten on the raft an additional recruit is viewed with anxiety; with fifteen, the sixteenth man is regarded with hostility; and as to the fatal seventeenth, if he is not shot or clubbed to death before he gets on board, it is because none of the others have weapons. And similarly, when we debate the restriction of immigration, we do not dissolve into philosophical inquiries as to whether it is the new increment to the population, or the population already here, or the total situation, that reduces wages. We strike at the effective margin, and thus defend our standard of life. It is not to be denied that the margin as a premise of formal logic may for certain theoretical purposes be more available than the effective margin....